Method and apparatus for cleaning a wellhead guide system



Nov. 6, 1962 w. J. HAYES 3,062,287

METHOD AND APPARATUS FOR CLEANING A WELLHEAD GUIDE SYSTEM Filed Dec. 12,1960 5 Sheets-Sheet l INVENTOR:

WILLIAM J. HAYES IS AGENT Nov. 6, 1962 w. J. HAYES 3,062,287

METHOD AND APPARATUS FOR CLEANING A WELLHEAD GUIDE SYSTEM Filed Dec. 12,1960 5 Sheets-Sheet 2 -47 49 rsz 3-5|- FIG. 2 A

INYENTOR:

WILLIAM J. HAYES Nov. 6, 1962 w. J. HAYES 3,062,287

METHOD AND APPARATUS FOR CLEANING A WELLHEAD GUIDE SYSTEM Filed Dec. 12,1960 5 Sheets-Sheet I5 INVENTOR WILLIAM J. HAYES BY 3? IS AGENT w. J.HAYES 3,062,287 METHOD AND APPARATUS FOR CLEANING A WELLHEAD GUIDESYSTEM Nov. 6, 1962 5 Sheets-Sheet 4 Filed Dec. 12, 1960 F I G. I2

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| NV E NTOR I W 1 LL I AM J. HAYES BY:IIH.-ZQ IS AGENT Nov. 6, 1962 w.J. HAYES 3,062,287

METHOD AND APPARATUS FOR CLEANING A WELLHEAD GUIDE SYSTEM Filed Dec. 12,1960 5 Sheets-Sheet 5 FIG. 9

FIG. IO

INVENTORZ WILLIAM J. HAYES .Hnwcaz ins AGENT nited States ware FiledDec. 12, 1960, Ser. No. 75,176 8 Claims. (Cl. 166-43) This inventionrelates to offshore operations concerned with drilling, producing,servicing, and maintaining underwater oil and gas wells, and pertainsmore particularly to methods and apparatus for making contact with aguide base of an underwater wellhead assembly positioned on or near theocean floor and for cleaning the marine growth or other deposits fromthe guide base, while operating from a remote location such as a vesselon the surface of the water, so that a plurality of guide lines can belowered into contact with the guide base and connected thereto.

A method of drilling and completing an underwater Well on the oceanfloor is described in copending application, Serial No. 830,538, filedJuly 30, 1959 to I-Iaeber et al. In the described method a wellheadassembly is permanently positioned on the ocean floor and a series ofguide lines extend from the wellhead assembly on the ocean floor to adrilling barge or other drilling vessel floating on the surface of thewater. Through the use of guide lines various pieces of equipment areraised and lowered between the wellhead assembly on the ocean floor andthe vessel on the surface. After well drilling operations have beencompleted, the guide lines are preferably removed in a manner describedin copending application, Serial No. 43,576, filed July 18, 1960 toHayes, so that they do not become a hazard to navigation of vessels inthe area. When it is desired at a later date to re-enter the well, theguide lines are attached to the guide base of the wellhead assembly onthe ocean floor by the method described in co-pending application,Serial No. 43,577, filed July 18, 1960 to Hayes.

In some areas and at some wellhead installations, it may not benecessary to go back and reconnect guide lines to the wellhead assemblyon the ocean floor for a number of years. Depending upon the depth ofthe water and the underwater conditions surrounding a wellhead assemblypositioned at or near the ocean floor, marine growth and other depositsincluding corrosion products may accumulate on the guide base positionedaround the wellhead assembly to which the guide lines are to beattached. It is therefore a primary object of the present invention toprovide a method and apparatus adapted to be lowered through a body ofwater to clean any marine growth or other deposits from the guidecolumns of a guide base.

A further object of the present invention is to provide a method andapparatus adapted to be lowered through a body of water and to beremotely aligned with each of the various guide columns of a guide basepositioned on the ocean floor whereby marine growth and/or otherdeposits may be cleaned from the guide column.

These and other objects of this invention will be understood from thefollowing description taken with reference to the drawing, wherein:

FIGURE 1 is a diagrammatic view illustrating a floatable drilling bargeanchored over a Wellhead assembly that is positioned on the ocean floor;

FIGURES 2 to 4 are schematic views illustrating the installation ofequipment between a drilling barge and a wellhead assembly on the oceanfloor for cleaning the guide base thereof;

FIGURE 5 is a longitudinal view showing one form atent of a cleaningtool for cleaning the inside of a tubular guide column;

FIGURE 6 is a longitudinal view of an orienting means carried within theguide frame of FIGURE 4;

FIGURE 7 is a longitudinal view taken in partial cross-section of theupper flange of the guide frame mandrel of FIGURE 4;

FIGURE 8 is a plan view of the upper flange shown in FIGURE 7;

FIGURE 9 is a longitudinal view in partial crosssection of the lowerflange carried by the guide frame mandrel of FIGURE 4;

FIGURE 10 is a plan view taken in partial crosssection of the bottomflange of the guide frame mandrel of FIGURE 4;

FIGURE 11 is a longitudinal view taken in partial cross-section ofanother form of a cleaning tool for cleaning post-type guide columns;and,

FIGURE 12 is a diagrammatic view of the cleaning tool of FIGURE 11 beingused to clean a post-type guide column.

Referring to FIGURE 1 of the drawing, a drilling barge 11, of anysuitable fioatable type is illustrated as floating on the surface of abody of water 12 and substantially fixedly positioned over a preselecteddrilling location, as by being anchored to the ocean floor by suitableanchors (not shown) at the ends of anchor lines 14 and 15. Equipment ofthis type may be used When carrying out well drilling operations inwater varying from about feet to 1500 feet or more in depth. Thedrilling barge is equipped with a suitable derrick 16 as well as otherauxiliary equipment needed during the drilling, completion ormaintenance of a well. The derrick 16 on the drilling barge ispositioned over a drilling slot or well 20 which extends verticallythrough the barge in a conventional manner. When using the equipment ofthe present invention, the slot 20 in the barge may be either centrallylocated or extend in from one edge. However, well location andmaintenance operations may be carried out over the side of the bargewithout use of the slot.

An equipment base assembly 17 including a wellhead assembly 18 is shownas being positioned on the ocean floor 13 and being anchored fixedlythereto by a conductor pipe or well casing 21 which extends into theocean floor I3 and is preferably cemented therein. For ease of operationthe slot 23 of the barge 11 is positioned substantially directly overthe equipment base 17 on the ocean floor. The equipment base 17 ofFIGURE 1 is provided with two or more guide columns 22, 23 and 24, onlytwo of which are shown in FIGURE 2 for ease of illustration. Preferably,each of the guide tubes 22 and 23 has a cone-shaped flange 25 and 26attached to its upper end which serves to align elements that enter theopen upper ends of the guide columns 22 and 23. Each guide column isprovided with a longitudinal slot 27 in the wall thereof extendingdownwardly from the open upper end of the column and is preferablypositioned in line with the center line through the wellhead assembly18. The wellhead assembly may be of any suitable type, the one beingillustrated is shown as being provided with a flowline 30, controlvalves 31, 32, 33 and 34, and a top closure 35 on the wellhead assemblywhich provides entry into the wellhead assembly by remote operationsfrom the drilling barge, if desired. The various valves and controlunits of the wellhead assembly 13 are either electrically, pneumaticallyor hydraulically actuated through a series of individual powertransmission lines which are grouped together in one or more bundles 36.

Fixedly secured to the equipment base 17 or to the wellhead assembly 18is a buoy line 37 of a length sufficient to extend from the underwaterinstallation to the surface of the water 12 where a buoy 38 is attachedthereto. The buoy line 37 may be in its normally extended position asillustrated in FIGURE 2, or a buoy container 40 may be provided in whichthe buoy line and its buoy 38 may be stored, to be brought to thesurface when it is desired to regain contact with the underwaterequipment base 17 and wellhead assembly 18. The buoy 38 can be releasedfrom its container 40 in any suitable manner, by power supplied throughone of the control lines in the transmission bundle 36 or by a signaltransmitted through the water to actuate a release mechanism in thecontainer or in the buoy which would release the buoy from thecontainer.

In practicing the method of the present invention, the mooring or buoyline 37 (FIGURE 2) serves as a guide line by which a string of tubing 41or drill pipe is guided down to the wellhead assembly 18. The lower endof the tubing string 41 is provided with a latching tool 42 of anysuitable type by which a rigid connection may be made with the top ofthe wellhead assembly 18. The form of the latching tool 42 illustratedis such that it is adapted to fit over the wellhead closure 35 and belocked thereon in any suitable manner, as by rotating or reciprocatingthe pipe string 41 or by applying hydraulic pressure therethrough. Thelower end of the latching tool 42 is preferably provided with a guidecone 43 to facilitate aligning the latching tool 42 on the top of thewellhead closure 35. The latching tool 42 is attached to a pair of guidearms 44 and 45 which in turn are secured to a guide tube 46 which isslidably mounted on the buoy line 37.

At the start of the operation of regaining contact with the underwaterwellhead assembly 18, the buoy 38 and the upper end of its line 37 wouldbe suitably anchored to the barge 11 at the surface in a manner suchthat the guide tube 46 can be readily slipped over it for movementtherealong. Throughout the well contacting operation an attempt is madeto maintain the buoy line 37 in a position as close to the vertical aspossible. With the guide tube 46 attached to the buoy line, the latchingtool 42 and the pipe string 41 are lowered in a conventional manner, asby means of a hoist in the derrick 16 on the barge 11, down through thewater until it is within the equipment base 17. The distance down to thewellhead 18 from the surface of the water is normally accurately knownfrom previous work on the well or by means of depth marks which could becontained on the buoy line 37. Thus, since the distance to the top 35 ofthe wellhead 18 is known, the guide cone 43 of the latching tool 42would be expected to contact the top 35 of the wellhead 18 when thepredetermined length of tubing string 41 had entered the water. If nocontact was made at that depth, the tubing string 41 and its latchingtool 42 is slowly moved in a circle or in any other desired patternabout line 37 until contact is established between the latching tool 42and the top of the wellhead assembly. With the latching tool 42 alignedover the top 35 of the wellhead assembly 18, continued lowering of thetubing string seats the latching tool 42 over the top of the wellheadassembly 18 where it can be locked into position.

If desired, in order to facilitate the alignment of the latching tool 42over the top 35 of the wellhead assembly 18, a light carrier 47 may beemployed which could be in the form of a tubular member of a diameter sothat it could slide over the tubing string 41 and have a pair of guidearms 48 and 49 that would be slidably mounted on the buoy line 37. Oneor more lights 51 and one or more television cameras 52 are suitablyarranged on the light carriage 47 so as to observe operations at thewellhead. The light carriage 47 is arranged for movement independent ofthe buoy line 37 or the tubing string 41 and may be raised and loweredby a hoist line 53. In FIGURE 2, the tubing string 41 and its latchingtool 42 are shown as being lowered through the water over the wellheadassembly 4 18. In FEGURE 3 the latching tool 42 at the lower end of thetubing string 41 is illustrated as being locked into place with thelight carriage 47 being raised to the surface again by means of hoistline 53.

With the buoy line 37 and the tubing string 41 extending from thewellhead assembly 18 to the drilling barge 11 (FIGURE 1), a guide frame54 (FIGURE 4) is lowered down through the water from the barge using thetubing string 41 as a guide. The guide frame 54 comprises any suitableframe or truss member, such for example as a pair of arms 55 and 56which are fixedly secured at one of their ends to a pair of collars 57and 58. The arms 55 and 56 may be interconnected by crossbracing members61 and 62. Fixedly secured to the other end of the arms 55 and 56 and tothe cross-bracing members 61 and 62 is a guide tube 66 which forms atubular bearing through which a string of pipe 64 extends. The pipestring 64 is rotatable within the guide tube 63 together with a cleanoutshoe 65 which is shown in greater detail in FIGURE 5.

When free to do so, the collars 57 and 58 of the guide frame 54 arerotatable in a horizontal plane and on a vertical axis about anorienting guide column 66 having upper and lower flanges 67 and 68secured thereto. The orienting guide column 66 (FIGURE 4) is providedwith tubular guide liner 71 (FIGURE 6) which is fixedly positionedthereto. The lower end of the guide liner 71 is cut in a mannerillustrated in FIGURE 6 so as to form a shoulder 72 extending from eachside of alongitudinal slot or keyway 73 down to a point 74. The keyway73 formed in the tubular guide liner 71 is designed to cooperate with along key 75 which is preferably welded to the outer surface of thetubing string 41 just above the latching tool 42. Thus, it will be seenthat as the top of the key 75 on the tubing string 41 contacts any pointof the shoulder 72 of the guide liners 71 carried within the orientingguide column 66 of the frame 54, the frame will be caused to rotateuntil the key 75 slides along the shoulder 72 and enters the keyway 73.While the key 75 on the tubing string 41 is fixedly positioned withregard to the orientation of any of the guide columns 22 and 23, thetubular guide liner 71 and its slot 73 may be positioned at any one ofseveral locations with respect to the frame 54, depending upon whichcolumn it is desired to have the cleanout tool 65 enter.

One means for selectively orienting the tubular guide line 71 and itsouter guide column 63 with respect to the arm 56 consists of providingthe flange 67 (FIGURE 7) with suitable connector means, such for exampleas set screws 77, 78 and 79 (FIGURE 8) so that the flange 67 can beremoved from the top of the tubular guide liner 71 at any time, whilethe orientation of the flange is always known when the flange 67 isconnected to the guide liner 71. One simple means of accomplishing thisis to provide the flange 67 with the three set screws 77, 78 and 79 sothat the flange 67 can only be attached to the top of the tubular guideliner 71 in one position, that is with a removable pin 82 which passesthrough the flange 67 oriented in a single position with regard to theslot 73 in the guide liner 71.

The collar 58 which is fixedly secured to the arm 56 (FIGURE 7) isprovided with a boss 83 (FIGURE 8) through which the pin 82 may extend.The boss 83 has a fixed position with respect to the arm 56. The lowerend of the pin 82 may be provided with a suitable holding pin 84 toprevent the pin 82 from becoming dislodged from its position during anyoperation. As shown in FIGURE 8, the upper flange 67 is provided with aseries of holes 85 and 86 and a hole 87, shown in FIGURE 7, which arearranged in a circle around the flange 67 so as to lie in knownorientation between the arm 56 (FIG- URE 8) and the slot 73 in thetubular guide liner 71 depending on which of the guide columns 22, 23,etc., in the equipment base assembly 17 (FIGURE 4) that it is desired tohave the cleanout tool 65 enter. Thus, if the three columns 22,23, and24 in the equipment base assembly 17 (FIGURE 1) are equally spaced 120to each other around a circle, the holes 85, 86 and 87 in the orientingflange 67 would also be spaced at 120 around the flange.

While a single orienting flange 67 is all that is needed at the top ofthe tubular guide liner 71 (FIGURE 7), because of the great weight ofthe equipment employed, it is preferable to have a second orientingflange 68 positioned near the bottom of the tubular guide liner 71 andits surrounding jacket or guide column 66. Thus, the lower collar 57,which is welded to the arm 55 and is rotatable about the guide column66, is provided with a boss 90 through which a pin 91 may extend. Thepin 91 may be provided with a holding pin 92 at the bottom thereof. Theflange 68 is provided with a series of holes 93, 94 and 95 (FIGURE 9)which are coaxial with the holes 35, 86 and 87 in the upper orientingflange 67.

As illustrated in FIGURE 4, the guide frame 54 is lowered down over thetubing string 41 with the tubing string 41 passing up through theorienting guide columns 66 attached to the guide frame 54 by means ofthe bolts 82 and 91 (FIGURES 7 and 9). Prior to lowering the apparatusthrough the water the pins 82 and 91 are seated in vertically alignedand selected holes. The guide frame 54 is lowered through the water bymeans of the pipe string 64 which extends to the vessel at the surfaceof the water and will later be rotated by equipment carried thereby. Ifdesired, the light carriage (FIGURE 3) with its lights 51 and televisioncamera 52 may follow the guide frame 54 down the tubing string 41 tocheck the operation of the wellhead. As the guide frame 54 and itsorienting guide column 66 approaches the top of the key 75 at the bottomof the tubing string 41, sufficient slack is provided in the buoy line37 to permit the frame 54 to be rotated about the tubing string 41 to apredetermined position above one of the guide columns 22, 23, etc.(FIGURE 4). With a rigid connection now formed between the guide frameand the wellhead assembly, the pipe string 64 is rotated from thesurface by suitable equipment carried on the vessel so as to cause therotating cleanout shoe 65 to clean out any marine growth or otherdeposits which may have formed on the inner wall of the guide columns22, 23, etc.

One type of a cleanout shoe is shown in FIGURE 5 which is provided witha pipe connection 96 at the top thereof for connecting it to the lowerend of the pipe string 64 (FIGURE 4). The cleanout shoe is equipped witha series of vertical or helical ribs 21 on the outer wall thereof(FIGURE 5) for scraping the inner wall of a guide column when the toolis rotated. Fluid ports 98 are preferably provided between the ribs 97and extend through the wall of the tool to allow a circulating fluidpumped down the pipe string 64 (FIGURE 4) to carry away material that isscraped from the wall of the guide column 22. A small circulating portmay also be provided out the bottom of the tool. In the event that thebottom of the guide column 22 (FIGURE 4) is provided with a hold-downshoe 100 of the type described in copending patent application, SerialNo. 43,577, filed July 18, 1960, the lower portion of the tool 65(FIGURE 5) is provided with an inwardly sloping face 101 which iscontoured to fit the sloping surface of the hold-down shoe 100 (FIGURE4) so that it will be properly cleaned. Also, spring-loaded dogs 102 and103 (FIGURE 5) may be provided on the lower portion of the tool 65 so asto be able to clean the under surface 104 of the hold-down shoe 100(FIGURE 4) adjacent the hole 105 therethrough. Each of the dogs, say103, is provided with upper and lower sloping faces 106 and 107 so thatthe radially retractable spring-loaded dog may be forced back into theshank 108 of the tool 65 (FIGURE 5) when the tool is forced down throughthe opening 105 (FIG- URE 4) or pulled up therefrom.

When the column 22 has been cleaned (FIGURE 4),

the frame 54 is raised to the surface again and the pins 82 and 91(FIGURES 7 and 9) are moved to another set of holes in the flanges 67and 68 so that when the frame 54 is again lowered down the tubing string41 in the abovedescribed manner, the cleanout shoe 65 and pipe string 64will be oriented over another preselected guide column, say guide column2.3.

In the event that the guide columns 22 and 23 have their guide cones 25removed and their upper ends closed so as to form a guide post asdescribed in copending application, Serial No. 43,577, filed July 18,1960, instead of a guide column, a different type of a cleanout toolwould have to be employed as the problem would then be to clean theouter surface of the guide post rather than the inner surface of acolumn. For cleaning guide posts a wash-over pipe similar to that shownin FIG- URE 11 may be employed. The wash-over pipe of FIG- URE 11comprises a large diameter length of pipe 109 being provided with aseries of ribs 110 on the inner surface thereof with the diameterbetween diametricallypositioned ribs being slightly greater than theoutside diameter of the guide post to be cleaned. The wash-over pipewould be provided with suitable coupling means 111 for connecting it tothe lower end of the pipe string 64,

through which a fluid could be pumped during cleaning operations. Whilethe present invention has been described with employing a frame 54(FIGURE 4) having a single guide tube 63 carried thereby to be alignedover one of the guide columns 22 in the base assembly 17 on the oceanfloor, it is realized that the guide frame 54 could be of the typedescribed in copending application, Serial No. 43,577, filed July 18,1960, which had a series of guide tubes 63, so that one would be inregister with each of the guide columns 22, 23, etc., of the baseassembly 17. Thus, with the guide frame 54 having multiple guide tubes63 carried thereby, the orienting flanges 67 and 68 could be eliminated.In operating with a frame of this type, after one of the guide columns,say 22, was cleaned out, the frame would be pulled to the, surface againand the pipe string 64 and its cleanout tool 65 would be moved toanother of the guide tubes 63, so that in being lowered again on thetubing string 41, the guide tube 63 aligned with the guide column, say23, would be in register so that the cleanout shoe 65 could be rotateddown through a second column. Other guide columns in the base assemblywould be cleaned by repeating the operation and moving the cleanout toolto a different guide tube each time. However, the weight of a frame ofthis type is so great that it is preferred to employ the smaller typeframe of the type described with regard to FIGURE 4 which is adapted tobe oriented by means of orienting flanges 67 and 68 so that one guidecolumn at a time can be cleaned out.

Instead of employing a pipe string 64 (FIGURE 4) to rotate the cleanoutshoe 65 or the wash-over shoe 109 (FIGURE 11) other suitable primemovers, such for example as electric motors or hydraulic turbines, whichcan be connected to the cleaning tools 65 and 109 and,

URE 4) with the guide tube 63 forming the tubular bearing between theprime mover means and the cleanout tool. As shown in FIGURE 12 of thedrawing, an electric motor 111 is connected in any suitable manner, asby brackets 112 to the top of the guide tube 63 of the guide frame 54.The shaft 113 of the electric motor 112 extends through the guide tube63 and is connected to the cleanout tool or wash-over shoe 109. In thiscase the length of the wash-over shoe 109 would be at least equal to thelength of the outer surface of a guide column 122 (FIGURE 12) that itwas desired to clean. Power could be supplied to the electric motor 111through a power transmitting cable 114 which is preferably combined witha cable of the weight-lifting type so that the motor and frame andcleanout tool could be lifted to the surface. In the event that thecleanout tool of the type shown in FIGURE 4 (element 65) were employedto clean out the guide column 22 when driven by the electric motor 111of FIGURE 12, it is quite apparent that the length of the tool 65(FIGURE 4) must be as long as the height of the guide column 22 which isto be cleaned. Otherwise, in the event that a short cleanout shoe 65(FIGURE 4) is employed, the electric motor 111 (FIGURE 12) would not besupported on or attached to brackets 112 but would be suspended from theend of the cable 114. In this case, the shaft 113 of the motor 111 wouldbe a length suflicient to enable the cleanout shoe 65 (FIGURE 4) to berun down through the guide column that it was cleaning out. In the eventthat the electric motor 111 was freely carried above the frame 54 withits shaft 113 slidably positioned within the guide tube 63, any suitabletype of anti-rotation device well known to the art may be employedbetween the electric motor 11 and the guide tube 63, such for example asa key similar to key 75 (FIGURE 4) and its associated keyway. Likewise,the electric motor 111 of FIGURE 12 could be replaced by a hydraulicturbine in which event the power transmitting cable 114 would be in theform of a hydraulic power transmitting pipe string through whichpressure fluid could be pumped to drive the turbine which in turn wouldrotate the cleanout tools.

Throughout the description of the apparatus of the present invention, itis assumed that in using the apparatus the guide columns 22 and 23(FIGURE 4) and any other guide columns that are attached to the baseassembly are all equi-distant from the center of the well and the tubingstring 41 attached thereto which serves as the pivot for the guide frame54. In the event that some of the guide columns on the wellhead baseassembly or any other type of assembly on the ocean floor are notequidistant from the tubing string 41, the arms 55 and 56 of the guideframe 54, which are preferably made adjustable, would have to beadjusted to their length to place a cleanout tool in register with thetop of the guide column to be cleaned.

I claim as my invention:

1. A method of remotely cleaning guide columns of an equipment basepositioned below the surface of a body of water, said method beingcarried out from an operational base positioned above the surface of thewater, said method comprising the sequential steps of positioning saidoperational base substantially directly above said equipment base,establishing a connection between said bases by lowering a pipe stringthrough the water to said equipment base, orienting the lower end ofsaid pipe string in register with the top of said wellhead on saidequipment base, seating the lower end of said pipe string on at least aportion of the wellhead, lowering through the water from saidoperational base and guiding along said pipe string a frame carryingcleaning tool means, orienting said frame to a predetermined positionabove and in contact with at least one guide column on said equipmentbase, and cleaning the surface of said guide column.

2 A method of remotely cleaning guide columns of an equipment basepositioned below the surface of a body of water, said method beingcarried out from an operational base positioned above the surface of thewater, said method comprising the sequential steps of positioning saidoperational base substantially directly above said equipment base,establishing a flexible connection between said bases by means of anelongated element, lowering a pipe string through the water along saidelongated element to said equipment base, orienting the lower end ofsaid pipe string in register with the top of said wellhead on saidequipment base, seating the lower end of said pipe string on the upperend of the wellhead, lowering through the water from said operationalbase and guiding along said pipe string a frame carrying cleaning toolmeans, orienting said frame to a predetermined position above and incontact with at least one guide column on said equipment base, cleaningthe surface of said guide column with a fluid during the cleaningoperation, and subsequently raising the frame to remove the tool meansfrom contact with said guide column.

3. A method of remotely cleaning guide columns of an equipment basepositioned around a wellhead below the surface of a body of water, saidmethod being carried out from an operational base positioned above thesurface of the water on a floating vessel, said method comprising thesequential steps of positioning said operational base substantiallydirectly above said equipment base, establishing a flexible connectionbetween said bases, lowering a pipe string through the water to saidequipment base, orienting the lower end of said pipe string in registerwith the top of said wellhead on said equipment base, seating the lowerend of said pipe string on the upper end of the wellhead, loweringthrough the water from said operational base and guiding along said pipestring a frame carrying cleaning tool means, orienting said frame to apredetermined position above and in contact with a guide column on saidequipment base, abrasively cleaning the surface of said guide column,raising the frame to remove the tool means from contact with said guidecolumn, aligning the frame and tool means successively with each of theother guide columns, lowering the frame into position above each of theother guide columns. and repeating the cleaning operation on each guidecolumn.

4. A method of remotely cleaning guide columns of an equipment basepositioned around a wellhead below the surface of a body of water on thefloor thereof, said method being carried out from an operational basepositioned above the surface of the water on a floating vessel, saidmethod comprising the sequential steps of positioning in an anchoredmanner said operational base substantially directly above said equipmentbase, establishing a flexible connection between said bases by a buoyline, lowering a pipe string through the water and guiding it along saidbuoy line to said equipment base, orienting the lower end of said pipestring in register with the top of said wellhead on said equipment base,seating the lower end of said pipe string on the upper end of thewellhead, lowering through the water from said operational base andguiding along said pipe string a frame carrying cleaning tool means,orienting said frame to a predetermined position above and in contactwith a guide column on said equipment base, abrasively cleaning thesurface of said guide column, flushing the surface of said guide columnwith a fiuid during the cleaning operation, raising the frame to removethe tool means from contact with said guide column, aligning the frameand tool means successively with each of the other guide column,lowering the frame into position above each of the other guide co umns,and repeating the cleaning operation on each guide column.

5. Apparatus for remotely cleaning guide columns of a subsurfacestructure from a remotely-located base above the surface of a body ofwater, said apparatus comprising an operational base positioned abovethe surface of a body of water, an equipment base assembly fixedlypositioned beneath the surface of a body of water, a plurality of guidecolumns extending upwardly from said equipment base assembly, a pipestring lowerable through said water to said base assembly, connectormeans carried by the lower end of said pipe string connectible to saidwellhead assembly of said base assembly, a carrier frame slidable alongsaid pipe string to said equipment base assembly, said frame includingtool support means disposed in a manner to register with the upper endsof the guide columns of said equipment base assembly, aligning meanscarried by said frame for selectively aligning the tool support means ofthe frame over at least one of the guide columns of said base assembly,and tool means carried by the tool support means for cleaning thecolumns.

6. Apparatus for remotely cleaning guide columns of a subsurfacestructure from a remotely-located base above the surface of a body ofwater. said apparatus comprising an operational base positioned abovethe surface of a body of water, an equipment base assembly fixedlypositioned adjacent the floor of a body of water, a plurality of guidecolumns extending upwardly from said equipment base assembly, a pipestring lowerable through said water to said base assembly, connectormeans carried by the lower end of said pipe string connectible to saidWellhead assembly of said base assembly, a carrier frame slidable alongsaid pipe string to said equipment base assembly, said frame including avertically-positioned bearing means disposed in a manner to registerwith the upper ends of the guide columns of said equipment baseassembly, aligning means carried by said frame for selectively aligningthe bearing means of the frame over at least one of the guide columns ofsaid base assembly, tool means carried beneath the bearing member inaxial alignment therewith, shaft means secured to said tool means andextending through said bearing member, and prime mover means carriedabove said frame for actuating said tool means.

7. Apparatus for remotely cleaning guide columns of a subsurfacestructure from a remotely located floating vessel on the surface of abody of water, said apparatus comprising a vessel having an operationalbase positioned above the surface of a body of water, an equipment baseassembly including an underwater wellhead assembly fixedly positionedadjacent the floor of a body of water, a plurality of guide columnsextending upwardly from said equipment base assembly, anchor meansextending from said base assembly into said floor to anchor said baseassembly thereto, a buoy line extending between said base assembly andsaid operational base, a pipe string lowerable through said Water tosaid base assembly, connector means carried by the lower end of saidpipe string connectible to said wellhead assembly of said base assembly,a guide frame affixed to the lower end of said pipe string and slidablealong said buoy line, a carrier frame slidable along said pipe string tosaid equipment base assembly, said frame including avertically-positioned tubular bearing member disposed in a manner toregister with the upper ends of the guide columns of said equipment baseassembly, aligning means carried by said frame for selectively aligningthe bearing member of the frame over one of the guide columns of saidbase assembly,

1t) rotatable tool means carried beneath the bearing member in axialalignment therewith, shaft means secured to said tool means andextending through said bearing member, and prime mover means carriedabove said frame for actuating said tool means.

8. Apparatus for remotely cleaning guide columns of a subsurfacewellhead assembly of an oil well drilled in the ocean floor andcompleted underwater from a remotely located floating vessel on thesurface of a body of water, said apparatus comprising a vessel having anoperational base positioned above the surface of a body of water, anequipment base assembly fixedly positioned including an underwaterWellhead assembly on the floor of a body of water, a plurality of guidecolumns extending upwardly from said equipment base assembly, a stringof pipe extending from said base assembly into said floor to anchor saidbase assembly thereto, a releasable buoy attached in a submerged mannerto said base assembly and adapted to float to the surface when released,a buoy line extendible between said base assembly and said buoy whensurfaced, a pipe string lowerable through said water to said baseassembly, connector means carried by the lower end of said pipe stringconnectible to said wellhead assembly of said base assembly, a guideframe affixed to the lower end of said pipe string and slidable alongsaid buoy line, a carrier frame slideable along said pipe string to saidequipment base assembly, said frame including a vertically-positionedtubular bearing member disposed in a manner to register with the upperends of the guide columns of said equipment base assembly, aligningmeans carried by said frame for selectively aligning the bearing memberof the frame over one of the guide columns of said base assembly,rotatable tool means carried beneath the bearing member in axialalignment therewith, shaft means secured to said tool means andextending through said bearing member, and prime mover means carriedabove said frame for actuating said tool means.

References Cited in the file of this patent UNITED STATES PATENTS

